Photodynamic therapy (PDT) is a cancer treatment modality that has shown promising results in terms of selectivity and efficacy, see e.g. Dougherty T J, et. al.: Photodynamic therapy, Journal of the National Cancer Institute 1998; 90: 889-905.
PDT relies on the use of a photosensitizer agent being activated by light in the presence of oxygen, leading to the production of toxic singlet oxygen radicals. Tissue destruction results from apoptosis, necrosis and vascular damage caused by these toxic singlet oxygen radicals.
In order to achieve an efficient treatment, several fibers have been used to ascertain that all tumor cells are subjected to a sufficient dose of radiation so that the toxic singlet state is obtained.
A limited penetration in the tissue of the activating light is a general issue of PDT. Only tumors less than about 5 mm in thickness may be treated by surface irradiation. In order to treat thicker and/or deeper lying tumors, interstitial PDT (IPDT) may be utilized. In interstitial PDT, light-conducting optical fibers are brought into the tumor using, e.g., a syringe needle, in the lumen of which a fiber has been placed, which is for instance described in PCT/SE2006/050120 of the same applicant as the present application, which hereby is incorporated by reference in its entirety for all purposes. However, PCT/SE2006/050120 does not provide a guidance concerning an effective positioning of a plurality of such optical fibers in a region of tumor tissue.
To optimize the biological effect in interstitial PDT, an accurate dosimetry method is needed and further a specifically devised planning prior the actual treatment of subjects is needed.
A pre-treatment planning of PDT is disclosed in PCT/EP2007/058477 of the same applicant as the present application, which hereby is incorporated by reference in its entirety for all purposes. A Method is disclosed that constitutes pre-treatment modules for IPDT on a whole prostate glandular tissue. The method includes reconstruction of the target geometry and optimization of source fiber positions within this geometry prior to beginning IPDT. However, the method of PCT/EP2007/058477 may further be improved, in particular with regard to information or guidance concerning determination of parameters of importance for pre-treatment or planning of the PDT, as well as adjustment thereof to particular patient situations.
Hence, there is a need for an alternative, or improved advantageous method and/or system for initially presetting, controlling and adjusting light therapy and/or related parameters before and during PDT in vivo or in vitro. In particular, the pre-treatment positioning of light sources in relation to a region of treatment may be improved.